Ministry spokeswoman Svenja Friedrich said that the motor transport agency had found that Audi diesel engines designed to meet the latest Euro 6 emissions standard offered “no reduction” of harmful nitrogen oxides under real driving conditions.

She said 77,600 of the cars were registered in Germany and that the affected models were: the A4, A5, A6, A7, A8, Q5, SQ5 and Q7. Audi must first agree on a fix with the agency and then notify owners of the repair action. An engine warming functions aimed at reducing emissions

Audi said the cars were already part of a voluntary upgrade action affecting some 850,000 vehicles to improve emissions performance. It said the problem was discovered as part of an analysis of all its diesel engines in cooperation with the authorities. It said engine management software would be modified, and that “as soon as the software has been approved we will inform the affected customers.”